1. Field of the Invention
The present invention relates to a press with a very large working surface for forming sheets by means of a pressure cell and a forming pad, influenced by the pressure cell, of elastic material which is pressed against sheets resting on a forming tool. In the press there may be manufactured plates for heat-exchangers, aircraft components such as ribs and the like.
The press according to the invention comprises a press stand with a window opening with a substantially rectangular cross-section. In the press stand a frame or plate is suspended, and in this there is attached a diaphragm which forms a pressure cell. On the underside of the diaphragm there is a thick layer of elastic material forming a pad which forms workpieces. Workpieces are placed on the bottom of a trough-shaped supporting member which is inserted into the working space below the plate with the pressure cell and the pad, whereafter the pressure cell is supplied with pressure medium which causes the pad to be pressed against one or more workpieces on the bottom of the trough-shaped supporting member. In such presses there are great problems with regard to preventing the pressing out of the pad through gaps between the supporting member and surrounding constructional elements in the presses. Particularly great are the problems of preventing pressing out of the pad through the gap between the upper surface of the supporting member and the supporting plate of the pressure cell at the end pieces of the press. Another problem with presses of this kind are deformations in the parts of the press stand, which causes deformation of the trough-shaped member and the forming tools and a reduced accuracy of measurement in the pressed products. In the manufacture of heat-exchanger plates these deformations constitute a serious inconvenience.
2. The Prior Art
In known constructions there is used, for example, an L-shaped strip which is resiliently attached to the part of the supporting plate of the pressure cell which forms an end wall in the space where the pressure cell and the pad are arranged. One flange of the L-shaped strip is attached directly by bolts to the end wall of the supporting plate and the resilience is obtained by bending the flange. By providing recesses in the flange, an increase in the amount of the elastic deflection is obtained. The forces which influence the strip during the pressing are great and sometimes cause the mounting bolts to break even after a short period of use. It has also been difficult to make the resilient parts of the strip flange to stand up against breakage. These bolt and strip ruptures have caused prolonged stoppages in operation. it has also been difficult to avoid the gaps between the ends of different strip parts, through which there is a risk of pressing out of the forming pad.